International efforts to end the conflict in southern Lebanon will reach a new level of urgency today when foreign ministers of the United States, Russia, France and Italy meet in Damascus to increase pressure for a ceasefire.

This follows a call last night from Russian and Western leaders, gathering in Moscow for today's nuclear summit, for an immediate end to the fighting. The French Foreign Minister, Herve de Charette, said France expected a ceasefire between Israel and Hizbollah within the next 24 hours.

"I am optimistic. We are now in a phase where people are working on an effective search for a solution. Unhappily we needed 250 dead, much damage and the butchery of Qana," Mr de Charette said.

Israel has already said it will call off its troops if Hizbollahagrees to stop firing. Syria and Lebanon pledged yesterday to put pressure on the Islamic militants. Lebanese Prime Minister, Rafik Hariri, said the fighting would end within five days.

US officials, galvanised finally by Thursday's massacre of Lebanese refugees by mis- directed Israeli shells, were hoping for an even swifter solution. But the Iranian spiritual leader Ayatollah Ali Khameini, speaking during Friday prayers, urged the militant Islamist guerrillas supported by Tehran, to "step up" their "heroic holy war" against the "Zionist usurpers".

Washington believes that, whatever Tehran may think, Syria holds the key to a rapid settlement. US officials hope that Damascus can persuade Hizbollah not only to cease firing rockets at northern Israel but to accept a longer-term settlement, reviving and strengthening a long-abandoned 1993 agreement in which both sides promised not to target civilians.

The US Secretary of State, Warren Christopher, will fly to Damascus today. Earlier, President Bill Clinton, speaking in Moscow, said: "We have a chance [to stop the shelling]". Edging the closest yet to even a mild rebuke to Israel, he said: "The parties have got to agree to a ceasefire ... [Otherwise] it's almost impossible for innocent civilians not to be hurt and killed."

The US won one diplomatic battle yesterday when - with British and French help - it defeated in the United Nations Security Council an attempt by Egypt to condemn Israel for the deaths of around 100 civilians at the UN base at Qana. The resolution adopted simply joined the international chorus of requests for an immediate ceasefire.